In a reflector antenna[?], the relative reduction in the effective aperture of the antenna caused by the masking effect of other antenna parts, such as a feed horn or a secondary reflector, which parts obstruct the radiation path.
... He also
gives prayers to Mary (cf. the De tabernaculis, and
Hortus rosarum, Pohl's ed., ut inf., i. also iii. 357,
vi. 219, 235 sqq.).
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